C4 LS swap a different perspective
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Well one of the other people in this thread (krusty84) said that the point of this thread is to build a "budget" car. Well, if you have to upgrade your 700r4 transmission with the heavier, newer parts from a later model transmission then what is that going to add to the cost of this "budget" car? A couple grand? More? Not to mention that the automatic cars come with the weak Dana 36 rear end that will not handle the extra power of even a mildly built LS engine. Now you've got to add the cost of swapping it out for a Dana 44 rear end which is better than the Dana 36 but still not capable of handling large amounts of horsepower. Most people that want to do an LS engine swap want to do it because of the large amount of power that can be made from an LS engine relative cheaply. Building a 600 horsepower LS engine won't cost too much but upgrading the rest of the drivetrain to be able to handle it WILL cost a lot. That's the whole point I've been trying to make. If you're not prepared to spend the kind of money that it's going to cost to upgrade the drivetrain to handle more power than it's capable of handling then you might as well just build the engine that's already in the car up to the maximum power level that the drivetrain can handle and call it a day.
Last edited by TheGreek!; May 2, 2019 at 04:22 PM.
Drifting
Joined: Mar 2018
Posts: 1,362
Likes: 400
From: DFW TX
What is funny is that although a mildly built 4.8/5.3 is going to produce great rwhp, they aren't torque monsters. They will likely produce similar or even less rwtq than a lightly modified L98. So the stock 700r and D36 probably aren't going to be all that much of a concern to begin with.
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
That's not what I'm trying to say. If you can afford to upgrade the drivetrain in it then by all means do so. C4s are great cars and worth upgrading but it will not be cheap to do it. The words "Corvette" and "budget" usually don't go together unless the word "large" is in front of the word "budget". I love my C4's and plan on upgrading the drivetrains eventually but I'm not going to lie to myself and think that's it's going to be cheap because it won't be.
Last edited by TheGreek!; May 2, 2019 at 05:19 PM.
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
Haha... Pretty much.
What is funny is that although a mildly built 4.8/5.3 is going to produce great rwhp, they aren't torque monsters. They will likely produce similar or even less rwtq than a lightly modified L98. So the stock 700r and D36 probably aren't going to be all that much of a concern to begin with.
What is funny is that although a mildly built 4.8/5.3 is going to produce great rwhp, they aren't torque monsters. They will likely produce similar or even less rwtq than a lightly modified L98. So the stock 700r and D36 probably aren't going to be all that much of a concern to begin with.
That's not what I'm trying to say. If you can afford to upgrade the drivetrain in it then by all means do so. C4s are great cars and worth upgrading but it will not be cheap to do it. The words "Corvette" and "budget" usually don't go together unless the word "large" is in front of the word "budget". I love my C4's and plan on upgrading the drivetrains eventually but I'm not going to lie to myself and think that's it's going to be cheap because it won't be.
That is basically what you said though. I just summarized it for you. I'm fairly perplexed by how much money some people can spend for such little result. I swapped a TH400 into my car for $200. Made a bracket in about 2 hours out of 1/4" plate steel to bolt it into the C-beam, and used the stock driveshaft. All I had to do was buy a proper length yoke and U joint, then used a cheap ebay flexible dipstick. Fit like a glove. That 3.07 rear gear meant that I can cruise the highway at a manageable RPM (2400, which is only 1/3rd of the rev limit of my 4.8). To the guys that have to buy everything, sure, it might be more expensive. The Corvette crowd seems to fall victim to that scenario more than any other crowd I've ever seen.
Burning Brakes
Joined: Nov 2015
Posts: 762
Likes: 94
From: Airdrie Alberta
I'm running a 2005 LQ9 (6L truck engine) on the stock 700R (reused the LQ9 flex plate) and dana 36. These days LS swaps are cheap and easy to find. The junk yards all over are filled with them.
Instructor
Joined: Jun 2019
Posts: 105
Likes: 15
From: Portland, Oregon
JoeNova,
The mechanics of the LSx swap aren't that tough. You've shown that. Dropping in a Gen III PCM and harness isn't even that tough. The problem with an LS swap in the late C4s is that the PCM sends a lot of data to the CCM over the ALDL serial bus. The CCM then drives the gauges. Without that PCM and serial connection in place I lose a lot of my dash functions, some HVAC functions and probably other things I haven't discovered yet. Do you have a solution for this? I also haven't come across solutions for retaining my ZF6 that are low buck. I think the +.400" thick swap McLeod flywheel would do it, but that's $405 alone.
So, for those of us wanting to retain the true GT (grand touring) nature of the C4, what's the real cost to swap an LT1/4, ZF6 car to an LS engine and not lose any functions except maybe the MPG/DTE fuel data?
The mechanics of the LSx swap aren't that tough. You've shown that. Dropping in a Gen III PCM and harness isn't even that tough. The problem with an LS swap in the late C4s is that the PCM sends a lot of data to the CCM over the ALDL serial bus. The CCM then drives the gauges. Without that PCM and serial connection in place I lose a lot of my dash functions, some HVAC functions and probably other things I haven't discovered yet. Do you have a solution for this? I also haven't come across solutions for retaining my ZF6 that are low buck. I think the +.400" thick swap McLeod flywheel would do it, but that's $405 alone.
So, for those of us wanting to retain the true GT (grand touring) nature of the C4, what's the real cost to swap an LT1/4, ZF6 car to an LS engine and not lose any functions except maybe the MPG/DTE fuel data?
Instructor
Joined: Aug 2017
Posts: 100
Likes: 1
From: Lafayette Indiana
https://tech.corvettecentral.com/201...-c4-corvettes/
IM all for LS swaps. Have guys in town with twin turbo 1000hp POS motors that keep kickin. There’s ways to make it work. Always is
especially with a Turbo400 lol
IM all for LS swaps. Have guys in town with twin turbo 1000hp POS motors that keep kickin. There’s ways to make it work. Always is
especially with a Turbo400 lol
Last edited by !!a2k!!; Dec 15, 2019 at 02:23 AM.
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Drifting
Joined: Mar 2018
Posts: 1,362
Likes: 400
From: DFW TX
Yea, I think LS swaps w/ 700r/4l60/th350/th400 can be done pretty easily and cheaply.
I think the huge disconnect between a lot of guys on this forum is simply over the details. Guys that have a nice car and wish to retain full functionality and have a very clean swap and guys that don't care much about that and just want a different platform that runs and drives and goes fast.
The swaps can be janked in there or done extremely well and there is a huge price and time/labor difference between the two.
I think the huge disconnect between a lot of guys on this forum is simply over the details. Guys that have a nice car and wish to retain full functionality and have a very clean swap and guys that don't care much about that and just want a different platform that runs and drives and goes fast.
The swaps can be janked in there or done extremely well and there is a huge price and time/labor difference between the two.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
Yea, I think LS swaps w/ 700r/4l60/th350/th400 can be done pretty easily and cheaply.
I think the huge disconnect between a lot of guys on this forum is simply over the details. Guys that have a nice car and wish to retain full functionality and have a very clean swap and guys that don't care much about that and just want a different platform that runs and drives and goes fast.
The swaps can be janked in there or done extremely well and there is a huge price and time/labor difference between the two.
I think the huge disconnect between a lot of guys on this forum is simply over the details. Guys that have a nice car and wish to retain full functionality and have a very clean swap and guys that don't care much about that and just want a different platform that runs and drives and goes fast.
The swaps can be janked in there or done extremely well and there is a huge price and time/labor difference between the two.
Instructor
Joined: Jun 2019
Posts: 105
Likes: 15
From: Portland, Oregon
https://tech.corvettecentral.com/201...-c4-corvettes/
IM all for LS swaps. Have guys in town with twin turbo 1000hp POS motors that keep kickin. There’s ways to make it work. Always is
especially with a Turbo400 lol
IM all for LS swaps. Have guys in town with twin turbo 1000hp POS motors that keep kickin. There’s ways to make it work. Always is
especially with a Turbo400 lol
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
Getting the engine in and power to the ground is not the hard part. Keeping all the goofy late C4 electronics working is the troublesome part. If you can't get the Gen III PCM to speak the 8192 baud ALDL serial protocol with the CCM or get the CCM to understand the Gen III PCM OBD-II then you have to put a protocol translator in the middle. I'm thinking I call Torqhead to see how they got the Gen III PCM and C4 CCM to communicate and see if he'd do the CCM work without me buying all the 24x LTx parts which an LSx obviously doesn't need.
For the later C4, 99.9% of the electronics can be wired independently of the CCM. None of the HVAC controls nor the rear defrost NEED the CCM to function, they are just simply controlled by it in the stock configuration. With a little extra time and very little money involved, you can wire them all just like any other car that doesn't have a CCM and retain normal functionality.
The gauges being the only exception. I'm not completely sure how the gauges handle the data. With the earlier cluster, you would just adapt all of your sensors on the new engine and the rest could be fairly easily configured to work with the stock cluster minus the MPG data.
Burning Brakes
Joined: Nov 2015
Posts: 762
Likes: 94
From: Airdrie Alberta
I've only dealt with the early C4. Much easier swap.
For the later C4, 99.9% of the electronics can be wired independently of the CCM. None of the HVAC controls nor the rear defrost NEED the CCM to function, they are just simply controlled by it in the stock configuration. With a little extra time and very little money involved, you can wire them all just like any other car that doesn't have a CCM and retain normal functionality.
The gauges being the only exception. I'm not completely sure how the gauges handle the data. With the earlier cluster, you would just adapt all of your sensors on the new engine and the rest could be fairly easily configured to work with the stock cluster minus the MPG data.
For the later C4, 99.9% of the electronics can be wired independently of the CCM. None of the HVAC controls nor the rear defrost NEED the CCM to function, they are just simply controlled by it in the stock configuration. With a little extra time and very little money involved, you can wire them all just like any other car that doesn't have a CCM and retain normal functionality.
The gauges being the only exception. I'm not completely sure how the gauges handle the data. With the earlier cluster, you would just adapt all of your sensors on the new engine and the rest could be fairly easily configured to work with the stock cluster minus the MPG data.
Instructor
Joined: Jun 2019
Posts: 105
Likes: 15
From: Portland, Oregon
The gauges in a late C4 like mine are driven by the CCM using a serial data stream provided by the PCM. The gauges don't handle the data, the CCM does. It seems more and more likely I will keep this car LT1 powered as it can be made to meet my modest power goals and I can tune the original PCM myself to accommodate the needed engine mods (cam, ported heads and intake manifold). Coil-near plug and more engine management features would be nice to have, but since 400 hp is enough for the open track events I do there's not much incentive to go LSx. If I just have to have turbo LSx power I'll find an earlier car that already needs an engine.
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
So here are my thoughts:
If I am going to build a race car there is nothing attaching me to a corvette and other options are available.
If my L98 C4 motor blew up tomorrow I would be looking for options. The car is a weekend and occasional driver. The things steering me away from an LS swap and keeping me in the SBC are the lack of a good way to interface the instrument panel and the difficulty with air conditioning (I live in Alabama). If you could solve those problems without cutting up the chassis, and my motor blew up, I would probably consider an LS swap.
As far as your headers go, not sure if you guys are selling full length or shortys. That said, if the stock manifolds fit from whatever donor I got I would probably use them as a first choice since they came with the motor and are "free". If they didn't fit my second choice would be a set of shortys designed for a C4/LS. If the only things out there were full length headers I would probably not go with an LS or fab my own shortys. I have had full length headers before and for me they wee just not worth the extra problems (leaks, sound, difficulty getting them in and out and working on the bottom of the engine.
Anyway, hope that helps answer your question. That is just me though so mileage may vary.
If I am going to build a race car there is nothing attaching me to a corvette and other options are available.
If my L98 C4 motor blew up tomorrow I would be looking for options. The car is a weekend and occasional driver. The things steering me away from an LS swap and keeping me in the SBC are the lack of a good way to interface the instrument panel and the difficulty with air conditioning (I live in Alabama). If you could solve those problems without cutting up the chassis, and my motor blew up, I would probably consider an LS swap.
As far as your headers go, not sure if you guys are selling full length or shortys. That said, if the stock manifolds fit from whatever donor I got I would probably use them as a first choice since they came with the motor and are "free". If they didn't fit my second choice would be a set of shortys designed for a C4/LS. If the only things out there were full length headers I would probably not go with an LS or fab my own shortys. I have had full length headers before and for me they wee just not worth the extra problems (leaks, sound, difficulty getting them in and out and working on the bottom of the engine.
Anyway, hope that helps answer your question. That is just me though so mileage may vary.
Last edited by auburn2; Dec 22, 2019 at 11:41 AM.
Melting Slicks
Joined: Mar 2016
Posts: 2,778
Likes: 580
From: Langley BC
I think the Ls swap dash issue has been largely solved on early C4's (Pre 1990). You basically just run a second set of stock C4 sensors in the LS and those give the dash its sensor data. You also run a regular set of LS sensors and that gives whatever computer system you decide to use Its sensor data. A lot of people don't do A/C with LS swaps but I've seen a number of pictures of people using readily avaliable high mount A/C LS brackets and Saden compressors. So I think most if not all the issues now have solutions. Wiring is of course always going to be a pain in ANY LS swap. On A Late C4 I wouldn't bother but i'm sure it could be done and some have done it sucessfully.
Last edited by DMITTZ; Dec 22, 2019 at 01:17 PM.
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
So here are my thoughts:
If I am going to build a race car there is nothing attaching me to a corvette and other options are available.
If my L98 C4 motor blew up tomorrow I would be looking for options. The car is a weekend and occasional driver. The things steering me away from an LS swap and keeping me in the SBC are the lack of a good way to interface the instrument panel and the difficulty with air conditioning (I live in Alabama). If you could solve those problems without cutting up the chassis, and my motor blew up, I would probably consider an LS swap.
As far as your headers go, not sure if you guys are selling full length or shortys. That said, if the stock manifolds fit from whatever donor I got I would probably use them as a first choice since they came with the motor and are "free". If they didn't fit my second choice would be a set of shortys designed for a C4/LS. If the only things out there were full length headers I would probably not go with an LS or fab my own shortys. I have had full length headers before and for me they wee just not worth the extra problems (leaks, sound, difficulty getting them in and out and working on the bottom of the engine.
Anyway, hope that helps answer your question. That is just me though so mileage may vary.
If I am going to build a race car there is nothing attaching me to a corvette and other options are available.
If my L98 C4 motor blew up tomorrow I would be looking for options. The car is a weekend and occasional driver. The things steering me away from an LS swap and keeping me in the SBC are the lack of a good way to interface the instrument panel and the difficulty with air conditioning (I live in Alabama). If you could solve those problems without cutting up the chassis, and my motor blew up, I would probably consider an LS swap.
As far as your headers go, not sure if you guys are selling full length or shortys. That said, if the stock manifolds fit from whatever donor I got I would probably use them as a first choice since they came with the motor and are "free". If they didn't fit my second choice would be a set of shortys designed for a C4/LS. If the only things out there were full length headers I would probably not go with an LS or fab my own shortys. I have had full length headers before and for me they wee just not worth the extra problems (leaks, sound, difficulty getting them in and out and working on the bottom of the engine.
Anyway, hope that helps answer your question. That is just me though so mileage may vary.
Drifting
Joined: Mar 2018
Posts: 1,362
Likes: 400
From: DFW TX
I think the Ls swap dash issue has been largely solved on early C4's (Pre 1990). You basically just run a second set of stock C4 sensors in the LS and those give the dash its sensor data. You also run a regular set of LS sensors and that gives whatever computer system you decide to use Its sensor data. A lot of people don't do A/C with LS swaps but I've seen a number of pictures of people using readily avaliable high mount A/C LS brackets and Saden compressors. So I think most if not all the issues now have solutions. Wiring is of course always going to be a pain in ANY LS swap. On A Late C4 I wouldn't bother but i'm sure it could be done and some have done it sucessfully.
If you install an LS, the car becomes unoriginal so what difference does it really make if you install an aftermarket gauge cluster?
I can understand folks not wanting to hack the K-member for the C5 A/C compressor location as there really is no reversal of that, but not wanting to do a swap because you can't use 24-30 year old gauges seems like a weak argument to me.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
I think the gauge cluster and A/C issues are just excuses for a lot of these guys because they hate the LS swap idea in general.
If you install an LS, the car becomes unoriginal so what difference does it really make if you install an aftermarket gauge cluster?
I can understand folks not wanting to hack the K-member for the C5 A/C compressor location as there really is no reversal of that, but not wanting to do a swap because you can't use 24-30 year old gauges seems like a weak argument to me.
If you install an LS, the car becomes unoriginal so what difference does it really make if you install an aftermarket gauge cluster?
I can understand folks not wanting to hack the K-member for the C5 A/C compressor location as there really is no reversal of that, but not wanting to do a swap because you can't use 24-30 year old gauges seems like a weak argument to me.
The A/C is interesting but like said, can be remedied. Custom length flex lines are pretty cheap and work just fine...
Instructor
Joined: Jun 2019
Posts: 105
Likes: 15
From: Portland, Oregon